Aug 30 2006
From The Space Library
Scientists reported that the ozone outside of Earth’s polar regions had begun recovering in 1997. This finding provided evidentiary support for international efforts to limit ozone-depleting substances. Researchers led by Eun-Su Yang of the Georgia Institute of Technology had examined ozone data that NASA satellites and other instruments had collected over a 25-year period. They had discovered that ozone in Earth’s stratosphere—the layer of atmosphere from 11 to 50 kilometers (6 to 31 miles) above Earth’s surface—had declined in thickness from 1979 to 1997 and then had ceased depleting. The results confirmed that the 1987 Montreal Protocol—an international treaty banning the production of ozone-depleting substances—had helped stop the loss of ozone, especially in the part of the stratosphere 18 kilometers (11.2 miles) above the surface of Earth. That stratospheric region contains the greatest concentrations of the chemicals banned by the treaty. The researchers also found substantial improvement of ozone in the stratospheric region below 18 kilometers (11.2 miles); they hypothesized that this alteration could be the result of changes in atmospheric winds.
NASA, “NASA, NOAA Data Indicate Ozone Layer Is Recovering,” news release 06-300, 30 August 2006, http://www.nasa.gov/home/hqnews/2006/aug/HQ_06300_Ozone.html (accessed 15 March 2010); Eun-Su Yang et al.,
“Attribution of Recovery in Lower-Stratospheric Ozone,” Journal of Geophysical Research 111, no. D17 (16 September 2006): D17309, http://www.agu.org/pubs/crossref/2006/2005JD006371.shtml (DOI 10.1029; accessed 29 June 2010).
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